Firstly, many-worlds interpretation explains the problems of spooky action at a distance and perceived hidden variables perfectly adequately. In fact it is the most popular interpretation these days, not the misleading Copenhagen interpretation.

Secondly, his hypothesis seems to be saying 'either particles and us are non-deterministic' or 'particles and us are deterministic'. This is hardly a profound statement since we are made of particles. Using the phrase free-will seems to be deliberately trying to oversell the theory as something more important than it is. Free will is a very vauge term with many different definitions, so it doesn't serve to use this language other than to sensationalise.